Dynamo-electric machine.



J. IL. BURNHAM.

DYNAMO ELECTRIC MACHINE. APPLICATION nun APR. 1, 1901.

PATENTED DEC. 17, 1907.

WEI E5555. Wl ENTUH ATTY gwumo (MUM flaw ururnn STATES PATENT OFF-Ion.

JOSEPH L. BURNHAM, OF SGHENEOTADY, NEW YORK, ASSIGNOR TOGENERAL'ELECTRIO OOM.PANY,,,A CORPORATION OF NEW YORK.

DirnAMo-ELEc'rnIc MACHINE.

Patented Dec. 17, 1907.

Application filed April 1 1907- Serial No.'365,678i

ing an armature connected both to a commu-' tator and to collector-ringsin which the relative voltages at commutator and collectorrings arevaried by varying'the distribution of flux on the faces of thefield-poles. Variation in the flux distributiondoes not affect thedirect current voltage which is determined solely by the total amount ofthe flux, While the effective alternating current voltage varies h withthe wave shape and, consequently, with the flux distribution- To reducethis flux variation, each pole is divi ed in planes parallel with thearmature axis into three portions, each provided with a magnetizingwinding, so that by varying the current-flow in the severalmagnetizingwindings the distri bution of flux in the field-pole -isyaried.

The object of my invention is to provide a machine which may be operatedin the manner described in the abovementioned 'patcuts, but which issimpler in construction and more economical in space and material. Tosecure this result, I take advantage of the fact that in a drum woundstructure each coil is composed of conductors se arated by about .180electrical de recs, sot at the induced voltage in the 00' may be variedby varying the fiuxatonly one of its sides. j

My invention consists in divlding each ole into two portions, one largerthan the 'ot er,

and placing the main winding on the larger" portion of thepole, and aregulating winding on the smaller portion. The two portions of each olecooperate in producing the effective.

. flux or inducing the directrcurrent'voltage,

so that when no current is flowing through the regulating winding thedirectcurrent' volta e is at an intermediate value, which may beincreased or decreased by passing current through the regulating windingin one direction or the other. Thealternating current voltage, on theother hand, is determined in amount not only bythe total m mmt of theflux, but also by its distribution, and variation of flux near the oletips has less effect on the effective in need alternating voltage thana-similar flux variation at the center of the pole. Consequently, if thecurrent in the main winding is kept constant while the current in theregulating winding is varied, the direct-current voltage may be varied-much more than the alternating current voltage. The flux distributionon the construction, but in a drum-Wound structure this produces nodissymmetry in-induced volta e for the reason mentioned above.

y'inven'tion will best be understood by reference to the accompanyingdrawings, in which Figure 1 shows diagrammatically a dynamo electricmachine arranged in accordance With my invention and connected for handregulatlon; and Fig. 2 shows the same machine arrangedfor automaticregulation.

In the drawings, A represents the arma-- ture which is provided with astandard drum winding and commutator, (not shown), and

der to simplify the drawing, are shown bear.- ing on the periphery ofthe armature. C represents collectorrings, to which threehaseconnections from the winding A are led.

D re resents the field magnet, each pole of which 1s divided in a planeparallel to the armature axis into two unequal portions d and d. Thesmaller portions (1 preferably face each other on ad acent poles, sincethis arrangement gives a symmetricatwave of'inducedelectromotive forcein the armature.

-E represents the main field winding, which surrounds-the main poleportions-d, and F represents, a regulating winding, which surrounds the;smaller portions d. g

e represents the usual field rheostat, while f represents a rheostat inseries with the regu lating winding.

G represents'a reversing switch in series with the regulating: winding.This winding may be supplied from any-separate source of excitation,or'rnay be connected directly to the direct-current bus bars H, as shownin the drawing.

' I re resents transformers through which the 'co lector-rings C areconnected to the alternating bus-bars J. The machine. as

pole faces is dissymmetrical with my pole the commutator'brushes B, B,which, inorthus connected, may serve either as a doublep,

current generator driven by power and sup plying energy to both thedirect and alternating-current bus-bars, or, may serve as a rotaryconverter deriving current from one set of bus-bars and delivering it tothe other.

Itwill be seen from an inspection of Fig. 1 that the direct currentvoltage induced between the (mmmutator brushes B B is determined by thesum of the fluxes in. the two portions of each pole. That is, it theregulating winding F is carrying no current, the voltage between thebrushes B B will be determined by the llu.\' in the pole portions (Z dueto the main licld winding l); and if current is sent through theregulating windingl the. voltage at the brushes I B will be increased ordiminished, according as the current in the regulating winding is insuch dil'cctiou as to produce a llux in the pole portiond', assisting oropposing the flux in the pole portion (1.

Variation of lluxin the pole portions d, however, has a much smallereil'ect upon the alternating-current voltage at the collectorrings (l.The reason for this is that the el fective induced alternating voltagedepends on the wave shape, and that a given amount of flux at the poletips has less etlect than the same amount of llux at the center of thepole,

while for the direct current voltage the distribution of the flux iswholly immaterial: so

that the current in the regulating winding may be varied to vary thedirect-current voltage without producing a proportional effect on thealternating-current voltage. Furthermore, though the flux distributionis dissyimnetrieal, the induced alternating voltage is symmetrical,since whena coil is either entering or leaving a pole area, one side ofit passes under a pole section (1, while the other side 1S0 electricaldegrees away passes under a pole section (1. i

In Fig. 2, the rheostat f and reversing switch G are omitted from thecircuit of the regulating winding F, and this winding is connected inseries with the armature brushes, so that the current through it isvaried automatically with the load o'n-the machine. In this way, themachine may be aut'omatieally compounded or over-compounded for varyingload.

I do not desire to limit myself to the particular construction andarrangement of parts here shown, but aim in the appended claims to coverall modifications which are within the scope of my invention.

hat I claim as new and desire to secure by Letters Patent of the UnitedStates, is,-

1. ln a d vnamo-electric machine, an armature winding connected both toa commutator and to collector-rings, a field magnet having poles dividedin planes substantially parallel with the armature axis into two unequalportions, a main field winding surrounding the greater portion of apole, and a regulating winding surrounding the smaller portion.

2. In a dynamo-electric machine, an armature winding connected both to acoinmutater and to collector rings, a field magnet having poles dividedin planes substantially parallel'with the armature axis into two unequalportions, a main field winding surrounding the greater portion of apole, a regulating'winding surrounding the smaller portion, and currentcontrolling means in circuit with said regulating winding.

3. In a ilynamo-electric 1nachine, an armature winding eonnected both toa commutator and to collector rings, a field magnet having poles dividedin planes substantially parallel with the armature axis into two unequalportions, a main iield winding surrounding the greater portion of apole, at regulating winding surrounding the smaller portion, and arheostat in circuit with said regulating winding.

4. In a dynamo-electric machine, an armature winding connected both to-acommutator and to collector rings, a 'Iield magnet having poles dividedin planes substantially parallel with the armature axis into two unequalportions, a main iield winding surrouinling the greater portion of apole, a regulating winding surrounding the smaller portion, and switchcontacts in circuit with said regulating winding.

5. In a dynamo-electric machine, an armature winding connected both to acoinmutator and to collector rings, a ii'eld magnet having poles dividedin planes substan tially parallel with the armatureaxis into two unequalportions, the smaller portion of one pole facing the smaller portiononan adjacent pole, a main 'licld winding surrounding the greater portionof a pole, and a regulating winding surrounding the smaller portion.

6. In a. dynanni-clectric machine. an armature winding connected both toa commutator and to collector rings, a iield magnet liaving polesdivided in planes substantially parallel with the armature axis into twounequal pm'tions,.the smaller portion ot one. pole facing the smallerportion on an adjacent pole, a main tield winding surrounding thegreater portion of" a pole. a regulating winding surrounding the smallerportion, and current-controlling means in circuit with said regulatingwinding.

In witness whereof, I have hereunto set my hand this 30th day of March.ltttlT.

JUSlllll ll. ld ltXllANl.

Witnesses:

BENJAMIN B. Hum. HELEN ()nronn.

